After telling Arjuna what not to do in 6.16, Krishna now describes what works. When food and leisure are measured, when effort in work is neither frantic nor lazy, when sleep and waking hours are balanced — that person's yoga becomes a destroyer of sorrow.
Three domains are named: eating and recreation, work and effort, sleep and waking. Balance in all three creates a stable platform for the inner life. When daily routine is chaotic, meditation becomes just one more source of frustration. When the routine is steady, meditation finds fertile ground.
Notice that Krishna uses the word 'yukta' three times in this single verse. Yukta means balanced, measured, connected. The repetition is deliberate — balance is not one decision but a pattern woven through every part of the day.